SCXI-1321 Terminal Block Installation Guide
10
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Assuming a strain-gauge range with a gauge factor of GF = 2 and a
quarter-bridge configuration, this range corresponds to ±1,498
µε
,
as given
by the strain formula for a quarter-bridge strain-gauge configuration:
where
Figure 3.
Quarter-Bridge Nulling Circuit
ε
4
V
r
–
GF
1 2
V
r
+
(
)
-------------------------------
=
V
r
strained voltage static unstrained voltage
–
V
exc
--------------------------------------------------------------------------------------------------------
=
CH+
CH+
CH–
EX+
EX–
+
–
+
–
R
1
R
2
4.5 k
Ω
4.5 k
Ω
R
SCAL
301 k
Ω
R
Trim
10 k
Ω
R
Null
39.1 k
Ω
(Screw Adjusts Potentiometer)
R
L
R
L
R
L
R
3
(dummy)
R
4
(gauge)
EX+
CH+
CH+
CH–
EX+
EX–
R
Trim
SCXI-1121
SCXI-1321
Transducer
V
EX
Note: R
1
and R
2
are completion resistors.
